The present invention relates to wind deflectors for vehicle sunroofs.
The sunroofs of vehicles, when open, produce significant noise levels which increase with the speed of the vehicle. Generally the noise is of a broadband nature due to pressure fluctuations resulting from the shear layer between the exterior air flow and the stationary air in the vehicle. In addition to this broadband noise, resonant interactions between the shear layer and the air inside the vehicle create low frequency pressure fluctuations which produce a booming noise over a critical speed range which is typically 30 to 70 miles per hour.
Conventionally, wind deflectors of uniform profile have been fitted to the leading edge of the sunroof aperture, so that they extend above the line of the roof when the sunroof is open, thereby deflecting the air flow away from the sunroof aperture. Wind deflectors of this form significantly reduce the broadband noise and also reduce buffeting of air within the vehicle. However they are not effective in reducing the `boom`. As a result, even with a wind deflector of this form, it is necessary to reduce the degree of opening of the sunroof in order to reduce the `boom` to acceptable levels, when travelling at speeds at which intense boom would otherwise occur.
It has been found, as disclosed for example in German patent specification numbers DE 3925808 and DE 4012569, that modifying the profile of the wind deflector, so that its upper edge is castellated, does provide some reduction in `boom` but the `boom` is still obtrusive at speeds within the critical range.
The present invention provides a wind deflector with modified profile which will significantly reduce `boom` at speeds within the critical range, with the sunroof fully open.